This page is dedicated to the discussion of converting Game Gear games to Master System games. Feel free to post any questions, comments, or even your own conversions. If you don't have real hardware to test (SMS/Genesis & a ROM cart), many readers here will offer to test for you.

If you're going to submit patches for review and to post on the GG2SMS page, please upload them as a zip file, using the following file formatting. I know it's a pain, but I've spent countless hours updating other people's formatting and it's very hard to keep up.

- Include your patch as an IPS file (NOT an SMS file), formatted to match the name found above, but add "-GG2SMS-#" at the end, with "#" being the version number.

- If an existing version of the patch doesn't already exist in the GG2SMS section, please include a screenshot of the title screen as a PNG, with the same formatting, but "-Title.png" at the end.

- If there's already a patch for the game, feel free to include any screenshot's you'd like in PNG format, showcasing your work.

- Include a readme.txt with all relevant info, including the date and versions.

- Save the above files (minimum the .ips and readme) as "-GG2SMS-#".

EXAMPLE OF NEW PATCH
Let's say I patched Aladdin and wanted to call it "version 1". I'd see that the games page is "http://www.smspower.org/Games/Aladdin-GG", so I'd create an ips patch labeled:
Aladdin-GG-GG2SMS-1.ips

I'd then take a screenshot of the title screen and name it (capital 'T'): Aladdin-GG-GG2SMS-Title.png

Finally, I'd create a readme.txt file that looked something like this:
Aladdin v1 by RetroRGB - 2015-12-31
* Start is Up+1
* Artifacts on menus and around the screen.

Then I'd zip them all into a file called: Aladdin-GG-GG2SMS-1.zip

EXAMPLE OF UPDATING SOMEONE ELSE'S PATCH
Let's say I wanted to add to Revo's Lost World patch - I'd download the current version and label mine the next revision number. At the time of this post, it's at v0.2, so I'd label mine: LostWorld-GG-GG2SMS-0.3.ips.

Posted: Thu Apr 24, 2014 12:42 pm Last edited by vingazole on Sat May 17, 2014 9:07 am; edited 4 times in total

Ok, let's start with Tempo JR. I attached the original ROM file, the IPS patch and the patched ROM to this post.

What I did on this conversion :

- accesses to the GG ports removed

- GG [Start] button replaced by the SMS [Pause] button in game and by [1] in the title screen

- Button [1] replaced by [2] in the cheat codes (the Hit & Hit Game doesn't work anymore for some reason that I don't understand !?)

- VDP's "left column blank" feature activated

- player and bosses life bars moved respectively to the top left and the top right corners of the screen

- GG palettes automatically converted to the SMS palettes format

The palette conversion is done on the fly while the palette in RAM is sent to VRAM, by only keeping the two most significant bits of each colour composant (red, green, blue) from the GG colour format :

I'll see if I can get something set up on the site for these. We might want to deal with hacks and modifications in general, rather than just GG ports. We are also interested in holding older versions for historical purposes.

For Tempo Jr I need to work on the palette of the stage 2, but I already done stage 1, others stages don't need update 'cause they are already good.

For Puzzle Bobble just 2 or 3 colors from the backround need to be change.

I also like to change the palette from the first Sega screen (the one from the game of course, not from the BIOS) to all black, like that you just have a black screen for 2 secondes and don't have to see 2 times the Sega logo.

- colours automatically converted (except for the orange, that I had to adjust - it was too close to the red)

- background tiles copied to enlarge the display

Excellent! This is probably one of the better conversions as of now. It's pretty much complete from what I have seen (no graphical glitches so far) and I didn't expect that mockup picture I did by enlarging the background tiles would turn up to reality!

I suppose it's very complicated to hack the 1p vs 2p mode so it could be functional on the Master System, right? That would be the only remaining thing to make this perfect.

Good, but for Sonic the Hedgehog Triple Trouble instead of the last version that was done in Sonic Retro maybe you should add the fix that was done afterwards by vingazole. Same goes for GG Aleste II / Power Strike II.

My guess is that most games uses the Gear-to-gear to share inputs and thus a hack to allow for 2 local players isn't out of reach for the type of games where both players are sharing the display. It isn't the case for Puzzle Bobble unfortunately. Very hard.

My guess is that most games uses the Gear-to-gear to share inputs and thus a hack to allow for 2 local players isn't out of reach for the type of games where both players are sharing the display. It isn't the case for Puzzle Bobble unfortunately. Very hard.

Oh, I thought the 1p vs 2p mode was like the 1p vs Computer mode, where there's actually a shared display with your CPU rival. Then I guess we are out of luck unfortunately.

A case where it could be possible then would be with hypothetical GG2SMS conversions of the first two Streets of Rage games. In both cases the Game Gear versions are different games to the Master System versions and do allow 2 players mode with shared display (unfortunately the Master System versions are 1 player only).

Good, but for Sonic the Hedgehog Triple Trouble instead of the last version that was done in Sonic Retro maybe you should add the fix that was done afterwards by vingazole. Same goes for GG Aleste II / Power Strike II.

I'll update the page with new links as Vingazole uploads them. No rush, I'll just update whenever he posts.

It's been a while since the last time I heard about GG2SMS conversions, it's nice that they are being discussed again.
By the way, I am the author of Sonic Drift 2 SMS, that I made almost five years ago, time passes just too fast.

Alright, yesterday I was playing a bit, so here is
Sonic Labyrinth SMS Release v1

It comes as an IPS patch and with source code for the code snippets, see the attachment.

From the readme:

Quote

...
This is the first release of this patch that allows you to play Sonic Labyrinth, a game released in 1995 by SEGA for the Game Gear, on your Master System.

The game works well, and is playable, but the screen except for the portion at the center that is what the Game Gear screen used to be, can get very scrambled.

As said before, that doesn't affect the game's playability, but can be aesthetically unpleasing; this bug may be fixed in a later release of this patch.

The Game Gear START button is mapped to Button 1 on the Master System, and does what START used to do on the Game Gear (pause, etc.)

The patch applies to a ROM image of the Sonic Labyrinth cartridge; as far as I'm aware only one version exists of it, and it was released in all territories (Japan, Europe and USA).
...

I don't have any flash cartridge at the moment, so I have not been able to test this on real hardware. I tested it on MEKA and Kega Fusion.
It would be really nice if someone could test the patched game on real hardware.

@RetroRGB: thank you for bringing up discussion about this, again. Also, nextvolume is my nickname, I used that other nickname just for a brief while.

Thanks so much for uploading! I just tested Sonic Labyrinth on an SMS and it works very well. I also tested it on Kega Fusion and both look identical, so I can assume whatever you saw in Kega is exactly what I'm seeing.

By the way, I'd never played that game before. It seems pretty neat...I'm really looking forward to trying it out now.

I have added this to the GG on SMS page and updated your nickname on both patches to nextvolume. Do you have a website or page you'd like me to link back to? I want to promote everyone's work as much as possible and hope more people will join in!

Also, would you happen to have the IPS patch for Sonic Drift 2? If not, no big deal, but I was hoping to get all of these patches in ips form.

Thank you for testing it on real hardware.
I have just made IPS patches for both Sonic Drift 2 and Sonic Triple Trouble and they are attached to this post.
I do not have a page about GG2SMS projects on my website, so you can just link to the index page.
My website is called Unhaut and the link to can be found by clicking the home page icon below this post (my post count does not allow me to post links, yet).

Awesome, thank you. Everything's updated. All I need now are the patches for Galga 2 / Galga 91'. Also, are there any other conversions out there I haven't stumbled upon yet?

I'm sorry if this is a stupid question, but is there a way to allow these games to access parts of the Genesis? Specifically the Start button and stereo sound? I assume no, since in order to play these games on a Genesis, it's in SMS mode, but I thought I'd ask anyway. Thanks again!

I also tested Sonic Labyrinth on hardware console, nice job nextvolume. It's always good to have new conversions for Sonic games since Sonic Triple Trouble and Sonic Drift 2 (I remember them being posted in the Sonic Retro forums). This is a good first step, but the game suffers a bit with the expanded resolution (especially during gameplay, where limited drawing distance can be a little bit confusing), even more than Sonic Drift 2.

Aside from that, maybe some people will tell you to have Game Gear "Start" button on "2" rather than "1", although I deem it fine in "1". This game benefits from having both Game Gear "1" and "2" buttons doing the same function (spin dash) so it isn't necessary to place the Game Gear "Start" button in button combinations or somewhere else.

Regarding Sonic Triple Trouble, vingazole did some fixes to the last version done by Glitch. That would be the ideal ips patch to have.

It is possible to use a Genesis controller in SMS mode, but it requires a bit of programming work to replace the controller reading code. I'm not sure how easy it would then be to also be SMS compatible.

is there a way to allow these games to access parts of the Genesis? Specifically the Start button and stereo sound?

The "stereo sound", in a Genesis, is limited to the YM2612 and not to the PSG, since the Game Gear is the only console of the bunch which can pan the PSG as well. I'm not sure if you can take control of the YM2612 in SMS mode, but I know you can mod your Genesis to install a YM2413. Sadly, iirc, the YM2413 isn't stereo, either.

Do you fancy adding pages? You have edit permissions now, have a play and see how you get on. Make sure to take the main Games page name and then append "-GG2SMS" to the URL. Bust-a-Move is not quite finished as I didn't have the tools to make screenshots on my phone.

Do you fancy adding pages? You have edit permissions now, have a play and see how you get on. Make sure to take the main Games page name and then append "-GG2SMS" to the URL. Bust-a-Move is not quite finished as I didn't have the tools to make screenshots on my phone.

It is possible to use a Genesis controller in SMS mode, but it requires a bit of programming work to replace the controller reading code. I'm not sure how easy it would then be to also be SMS compatible.

Its fairly easy, with the genesis controller you have to read the controls twice, then you just have to check on the second read if the left and right buttons are pressed (both on 0). if so, than you are reading from a genesis controller, since it's impossible to have both buttons pressed.
With the Genesis controller those bits always are on 0 on the second reading.
I am working on a project thats use the Genesis controller. In my case, I test the controller before the game begins, and set the proper routine to do the readings after that, but it's easy to convert the megaDrive reading rotine to test the controller each reading.

;Set TH hi for the next pass
ld a, Th.hi
out ($3F), a
jp endControlReading
.ends

It's also worth note the necessary delays between the outs($3f) and the readings. In the test routine they are just the push/pop hl. On the reading routine, the delays are the time between two readings for the first reading and the pause to start mapping in the second reading.

So it turns out that there's a better format than IPS - I hadn't checked since about 2003 - so I suggest we should go for UPS patches from now on. This gets us more reliable expansion, checksums on the input, and reversibility. I'll fix up the translation patches we have. Software here: www.romhacking.net/utilities/519/

Well, most emulators allow for that, and it's especially useful for TAS purposes.

Well, I was just thinking in real hardware. But it will work with a few adjustments.

1) if on the second reading you dont get a 00 on the left and right positions, you already know that its not a genesis controller, so there's no need to test anymore

2) if you get a 00 on the second reading, but also get on the first reading, than you actually have both buttons pressed, so, in this case, you can't take any conclusions

3) if you have 00 on the second reading, but not on the first reading than you most likely have a genesis controller.

4) there's another test you can make. that's is to verify if the buttons status are different between the first and second reading. If so, you know you most likely have a genesis controller.

Well, none of this is 100% conclusive, but apply all of then is not that hard and they are pretty good. And if you verify this before the game begins, you will have a wrong anwser only if the user is actually trying to break the test.

So it turns out that there's a better format than IPS - I hadn't checked since about 2003 - so I suggest we should go for UPS patches from now on. This gets us more reliable expansion, checksums on the input, and reversibility. I'll fix up the translation patches we have. Software here: www.romhacking.net/utilities/519/

Actually the author of the UPS format quickly replaced it with another format called BPS. He insists others follow (the only advantage I recall UPS had was reversibility, which he admits has pretty limited practical use).

Hey, here 2 conversions who are not finish at all but that can be play.

(I just adapt the conversion palette code of Vingazole and remap the start button).

Start is configure on button down of controler 2.

Should work on real hardware like I removed the GG ports and fixed the checksum.

The games are Captain America and the Avengers and Super Return of the Jedi.

Enjoy.

Stuff to do for both game:

- Take of the garbage screen on menus.
- Put black on the right of the screen ('cause you can see previous decor but sometimes it's good, there is maybe a way to fix that).
- Put black on the left of the screen like Vingazole did for Tempo Jr.
- Move the life bar.
- Take off the Sega first sreen (easy for me).

The conversion trend from the Game Gear to the Master System is now having a boost like it never had before. This is really good for the Master System games library.

But I wouldn't remove the Sega screens from the games if you ask me, just because that was the usual procedure Sega did with their Master System releases. In fact, there are several official Master System games which do keep the Sega screens, like the Streets of Rage games.

Posted: Wed May 14, 2014 5:00 pm Last edited by Revo on Wed May 14, 2014 5:09 pm; edited 1 time in total

I don't know how to do IPS patch sorry, and I don't like this kind of stuff.

I'm not working on Fatal Fury at the moment 'cause Vingazole want to work on it.

I've been working on The Itchy & Scratchy Game and I'm pretty sure that the game was developed for Master System on the first place and then adapted for the Game Gear.
'Cause of that, my conversion don't seems like a GG conversion but like a real Master System game, no glitch at all, it's really nice.
I just need to ask 2 things to Vingazole for the conversion to be finish:
- You can do Pause during the game, I would like this action to be configure on the button pause of the Master System (It's configure on button down controler 2 right know but the pause stay just 1 sec, strange shit...).
- Moving the 2 life bars on the corners.

For this game I didn't adapt the palette code of Vingazole, but I changed all the palettes colour by colour (it's actually one of the only game you can do that without glith).

The rom will not be public 'cause I want some exclusivities for my website/shop.

To finish, I'm glad to present you my conversion of Buster Ball.
Start button map on button down controler 2.
No glitch until the first goal (after you have nice garbage screen around the screen; there is probably a way to fix that).
Ready to work on real hardware. Download below.

Thank you RetroRGB for the update of your page (the link of my shop on it is much appreciate).

No problem! I really want to promote everyone's work, as a thanks for all the effort. You guys are all making Game Gear fans very happy!

Revo wrote

You should edit your first post to put your link on it ;)

Good idea. I updated it with both pages and will remove mine after the SMSPower page is complete.

Revo wrote

To finish, I'm glad to present you my conversion of Buster Ball.
Start button map on button down controler 2.
No glitch until the first goal (after you have nice garbage screen around the screen; there is probably a way to fix that).
Ready to work on real hardware. Download below. Enjoy.

To finish, I'm glad to present you my conversion of Buster Ball.
Start button map on button down controler 2.
No glitch until the first goal (after you have nice garbage screen around the screen; there is probably a way to fix that).
Ready to work on real hardware. Download below.

Enjoy.

What's the way to restore the introductory Sega screen?

It doesn't seem to be removed, but only turned into a black screen somehow. I would like to get it back as it was.

If it's there, but black, you can try editing the palette in Meka while frozen at that point; if that works, you can try to find where the palette is set and see if you can edit it. It might need some extra code.

To map the pause button, you need to write some code at address $66. This is executed when the pause button is pressed. You should make it set a flag in memory, maybe use the address where the original code put the start button status. However, this will never unset the flag, so you need to alter the code which reads the flag so it clears it after reading.

Game Gear games use offset $66 for the Gear to Gear link. If the game supports multi player, you will find existing code there which you can overwrite with care. Otherwise you'll find nothing there and you'll need to find space for the extra code.